Concrete floors are durable but can feel cold and lose heat without proper insulation. Choosing the right insulation helps with energy efficiency, moisture control, and long-term cost savings. This guide compares the best insulation types for concrete floors, their R-values, costs, and uses, helping you decide which is right for your project.
| Insulation Type | R-Value per Inch (Thermal Resistance) | Best For | Moisture Resistance | Compression Strength | Cost per m² (£) | Ease of Installation |
|---|---|---|---|---|---|---|
| Rigid Foam Board (EPS) | 3.6 – 4.2 | General concrete subfloor insulation, basements, and radiant heating systems. | Moderate – Can absorb moisture if not sealed properly. | Medium – Can support light loads. | £10 - £20 | ✅ Easy – Lightweight and cuttable. |
| Extruded Polystyrene (XPS) | 4.5 – 5.0 | High-moisture areas, garages, and commercial floors. | High – Water-resistant and great for damp environments. | High – Can support heavy loads. | £15 - £25 | ⚠️ Moderate – Needs precise cutting and sealing. |
| Polyisocyanurate (PIR) | 6.0 – 7.0 | High-performance insulation for energy-efficient buildings. | High – Foil-faced PIR is excellent at resisting moisture. | Medium – Can compress under extreme loads. | £20 - £35 | ⚠️ Moderate – Requires foil taping for full efficiency. |
| Spray Foam Insulation | 5.5 – 6.5 | Uneven or irregular concrete surfaces, tight spaces. | High – Creates an airtight, moisture-resistant barrier. | Low – Not as strong under direct loads. | £30 - £50 | ❌ Hard – Requires professional application. |
| Insulated Concrete Forms (ICF) | 5.0 – 6.0 | New builds where concrete and insulation are integrated. | High – Acts as a permanent moisture barrier. | Very High – Integral to the concrete structure. | £40 - £80 | ⚠️ Complex – Best for large-scale construction. |
| Glass Wool or Mineral Wool Boards | 3.0 – 4.0 | Soundproofing and thermal insulation for above-grade floors. | Low – Can absorb moisture if exposed. | Low – Best when combined with a rigid layer. | £10 - £18 | ✅ Easy – Can be cut and laid by hand. |
The best insulation depends on where the floor is located. XPS (extruded polystyrene) is great for basements and damp areas, while PIR boards provide high thermal resistance for energy-efficient builds.
It absolutely does, concrete has a high thermal mass, meaning it absorbs and loses heat easily. Without insulation, a concrete floor loses heat in winter and feels cold underfoot year-round.
Again, yes you should, insulation prevents heat loss from underfloor heating systems, ensuring warmth stays inside your home instead of escaping into the subfloor.
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